Abstract
BACKGROUND: The relationship between self-reported physical function (PF) and objective performance in patients with stroke remains unclear. This study explored how various self-reported health domains influence the correlation between Patient-Reported Outcomes Measurement Information System (PROMIS) PF and the Timed Up and Go (TUG) test. METHODS: A retrospective cohort study examined patients with stroke who completed the TUG and PROMIS PF within 90 days post stroke. Correlations between these measures were analyzed, both overall and stratified by performance on other patient-reported outcomes (Quality of Life in Neurological Disorders cognitive function, depression, and the following PROMIS scales: global health, social satisfaction, pain, sleep, and fatigue). Structural equation modeling assessed how these patient-reported outcomes influenced the PROMIS PF-TUG relationship. RESULTS: There were 432 patients with average age 63.7 (SD 13.5) years. Average TUG and PROMIS PF scores were 16.6 (SD 10.4) seconds and 36.8 (SD 8.5), respectively. TUG and PROMIS PF showed moderate correlation (r=-0.47 [95% CI, -0.54 to -0.40]). Fatigue (r=-0.53 [95% CI, -0.59 to -0.45]) and satisfaction with social roles (r=0.53 [95% CI, 0.45 to 0.60]) had the strongest correlations with PROMIS PF. Both social roles (estimate=0.08, SE=0.02, P=0.001) and fatigue (0.06, SE=0.02, P=0.001) demonstrated indirect effects on the TUG-PROMIS PF relationship. Although not significant, correlations between PROMIS PF and TUG scores were consistently weaker in patients with poor scores in any patient-reported outcome. CONCLUSIONS: There is only moderate correlation between self-reported PF and the performance measure TUG, which is mediated by fatigue and satisfaction with social roles. These findings highlight the importance of considering these broader dimensions of health in addition to physical capacity when interpreting patient-reported PF scores.